<style>
.size{
     height:10px;
}
#p1{
     background:red;
}
#p2{
     background:orange;
}
#p3{
     background:yellow;
}
#p4{
     background:green;

}
#p5{
     background:cyan;
}
#p6{
     background:blue;
}
#p7{
     background:purple;
}
</style>

<div id="p1" class="size"></div>
<div id="p2" class="size"></div>
<div id="p3" class="size"></div>
<div id="p4" class="size"></div>
<div id="p5" class="size"></div>
<div id="p6" class="size"></div>
<div id="p7" class="size"></div>